A new isoflavonol and other constituents from Cameroonian propolis and evaluation of their anti-inflammatory, antifungal and antioxidant potential.

Propolis is rich in diverse bioactive compounds. Propolis samples were collected from three localities of Cameroon and used in the study. Column chromatography separation of propolis MeOH:DCM (50:50) extracts yielded a new isoflavonol, 2-hydroxy-8-prenylbiochanin A (1) alongside 2',3'-dihydroxypropyltetraeicosanoate (2) and triacontyl p-coumarate (3) isolated from propolis for first time together with seven compounds: ß-amyrine (4), oleanolic acid (5), ß-amyrine acetate (6), lupeol (7), betulinic acid (8), lupeol acetate (9) and lupenone (10). These compounds were tested for their inhibitory effect on oxidative burst where intracellular reactive oxygen species (ROS) were produced from zymosan stimulated human whole blood phagocytes and on production of nitric oxide (NO) from lipopolysaccharide (LPS) stimulated J774.2 mouse macrophages. The cytotoxicity of these compounds was evaluated on NIH-3 T3 normal mouse fibroblast cells, antiradical potential on 2,2-diphenyl-1-picrylhydrazylhydrazyl (DPPH·) as well as their anti-yeast potential on four selected candida species. Compound 1 showed higher NO inhibition (IC50 = 23.3 ± 0.3 µg/mL) than standard compound L-NMMA (IC50 = 24.2 ± 0.8 µg/mL). Higher ROS inhibition was shown by compounds 6 (IC50 = 4.3 ± 0.3 µg/mL) and 9 (IC50 = 1.1 ± 0.1 µg/mL) than Ibuprofen (IC50 = 11.2 ± 1.9 µg/mL). Furthermore, compound 1 displayed moderate level of cytotoxicity on NIH-3 T3 cells, with IC50 = 5.8 ± 0.3 µg/mL compared to the cyclohexamide IC50 = 0.13 ± 0.02 µg/mL. Compound 3 showed lower antifungal activity on Candida krusei and Candida glabrata, MIC of 125 µg/mL on each strain compared to 50 µg/mL for fuconazole. The extracts showed low antifungal activities ranging from 250 to 500 µg/mL on C. albicans, C. krusei and C. glabrata and the values of MIC on Candida parapsilosis were 500 µg/mL and above. DPPH* scavenging activity was exhibited by compounds 1 (IC50 = 15.653 ± 0.335 µg/mL) and 3 (IC50 = 89.077 ± 24.875 µg/mL) compared to Vitamin C (IC50 = 3.343 ± 0.271 µg/mL) while extracts showed moderate antiradical activities with IC50 values ranging from 309.31 ± 2.465 to 635.52 ± 11.05 µg/mL. These results indicate that compounds 1, 6 and 9 are potent anti-inflammatory drug candidates while 1 and 3 could be potent antioxidant drugs.

Deciphering composition and connectivity of a natural product with the assistance of MS and 2D NMR.

A complementary application of three analytical techniques, viz. multidimensional nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS), and single-crystal X-ray diffractometry was required to identify and refine two natural products isolated from Millettia versicolor and solvent of crystallization. The two compounds, namely 3-(2H-1,3-benzodioxol-5-yl)-6-methoxy-8,8-dimethyl-4H,8H-pyrano[2,3-h]chromen-4-one, or durmillone, (I), and (2E)-1-(4-{[(2E)-3,7-dimethylocta-2,6-dien-1-yl]oxy}-2-hydroxyphenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one, (II), could not be separated by routine column chromatography and cocrystallized in a 2:1 ratio with 0.13 molecules of ethanol solvent. Compound (II) and ethanol could not be initially identified by single-crystal X-ray analysis due to complex disorder in the aliphatic chain region of (II). Mass spectrometry ensured that (II) represented only one species disordered over several positions in the solid state, rather than several species cohabitating on the same crystallographic site. The atomic identification and connectivity in (II) were established by several 2D (two-dimensional) NMR techniques, which in turn relied on a knowledge of its exact mass. The derived connectivity was then used in the single-crystal analysis to model the disorder of the aliphatic chain in (II) over three positions and allowed identification of a partially occupied ethanol solvent molecule that was disordered over an inversion center. The disordered moieties were refined with restraints and constraints.

Identification of an anti-inflammatory principle from the stem bark of Millettia versicolor.

The dichloromethane-soluble fraction of the methanol extract of the stem bark of Millettia versicolor Welw. (Leguminosae) has been shown to possess anti-inflammatory activity. The chromatographic fractionation and subsequent analysis of the spectroscopic data of this extract led to the isolation and identification of 2-acetyl-7-methoxynaphtho[2,3- b]furan-4,9-quinone (1) along with two known quinones. Pharmacological data demonstrate that compound 1 has relevant anti-inflammatory properties whereas the other two isolated compounds do not.

Griffonianone D, an isoflavone with anti-inflammatory activity from the root bark of Millettia griffoniana.

A new isoflavone, griffonianone D (1), and the previously known compounds durmillone and odorantin were isolated from a chloroform extract of the root bark of Millettia griffoniana. The structure of 1 was established as (7E)-(6",7"-dihydroxy-3",7"-dimethyloct-2"-enyl)oxy-4'-methoxyisoflavone on the basis of its spectral data. The chloroform extract of the root bark of M. griffoniana and compound 1 showed anti-inflammatory effects in different experimental models of inflammation.